Box base



FIG. 1 is a perspective view of a box base showing my new design;

FIG. 2 is a right side elevation thereof; the left side elevation being a mirror image thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a front elevation thereof; and

FIG. 6 is a rear elevational thereof.

The broken lines showing of a box cover is for illustrative purpose only and forms no part of the claim. 

The ornamental design for a box base, as shown and described. 